Secondary electron emission tube



Jan. 11, 1949. W. soLLER I SECONDARY ELCTRON EMISSION TUBE l Original Filed Aug. 19, 1945 DNN Patented Jan. 11, 1949 SECGNDABY ELECTRON EMISSION TUBE Walter Seller, Cincinnati, Ohio, assigner of onehalf to William Calif.

H. Woodin, r., San Mateo,

Original application August 19, 1943, Serial No. 499,260. Divided and this application August 28, 1944, Serial No. 551,513

(Cl. Z50-27) 4 Claims.

My invention relates broadly to electron tubes and more particularly to a deflection type of secondary electron emission tube for wide application in the electronic industry.

This application is a division of my application Serial No. 499,260 for Electron tube filed August 19, 1943.

One of the objects of my invention is to provide a construction of deflection type secondary electron emission tube having associated input and output circuits wherein substantially complete isolation of the input from the output circuit is effected.

A further object of my invention is to provide a construction of secondary emission electron tube operating as an electron multiplier in which complete isolation of the input and output circuits is maintained.

Other and further objects of my invention reside in the construction of an improved electron multiplier tube as set forth more fully in the specication hereinafter following by reference to the accompanying drawings in which:

Figure 1 is a schematic View of the electron multiplier tube of my invention; Fig. 2 is an enlarged sectional view of the secondary electron emitting electrodes and plate assembly of the electron multiplier tube of Fig. 1; and Fig. 3 is a transverse sectional view of the anode and secondary electron emitting' electrodes taken on line 3 3 of Fig. 1.

In Fig. 1 I have shown my invention applied to an electron multiplier type of tube l. In this arrangement the secondary emission plate system is formed by a plate-like envelope 18 folded upon itself with the front and rear portions of the envelope spaced from each other for enclosing the grid element 88 therein. The secondary electron emitting portions of the plate system 18 are represented at 1S, having a V-shaped cutout therein for controlling the secondary electron emission as the area of the plate is swept by the electron beam from generator G.

The electron beam generator G is illustrated as including the electron emitter represented generally at 4, the beam forming plates shown at 5, 6 and 6 and the deflecting plates indicated generally at 1 and 8. These several elements are suitably supported by wire members extending through the end of the tube I. The deecting plates 1 and 8 are connected to the input system shown generally at 40. It will be observed that the input system 40 is entirely isolated from the output system indicated at 4I. A connection is completed Y between triangular recessed plate member 19 and the grid electrode 88 through the potential source 51. A predetermined potential dilerence is established between the electron beam generator G and the plate electrode 1Q through direct current source 31. The horizontal electron beam which emanates from the electron generator G is as wide as the upper edge portion of the triangular shaped plate member 18 and as ythe input across deflecting plates 1 and 8 is changed, the beam deects vertically in a downward direction scanning the narrowing surface of the recessed plate member 19 accompanied by the release of a smaller number of secondary electrons which travel to secondary electron emitting electrodes 8l, 8i', 82, 82', 83, 83, 84, 84', 85, 85', 86, 88', 81 and 81. As the electron beam is deflected upwardly due to increased voltage on the input plates 1 and 8, the secondary electrons released from the surface of triangular recessed plate 19 increases from a very small amount adjacent the apex 19a in its lower position to a maximum amount adjacent each limiting position approaching the edge portions at the shields 19h and 19e.

The portions 19 of the plate meet at the apex portion 19a of the V-shaped cutout. The grid 8D is shown disposed behind the portions 13 of the plate system. In order to effectively direct the secondary electron emission from portions 19 of the plate system, I arrange shields 19o and 13e adjacent the peripheral edges of the plate system in a position for shielding electronic discharge in the direction of any of the multiplier platee` other than the sets of multiplier plates 8l and 8 l A plurality of multiplier plates are arranged in the trajectory of secondary electrons initiallyrdischarged from multi-plier plates 8l and 8l.

I have shown more clearly in Fig. 2 the plurality of multiplier plates at 82, 83, 84, 85, 86 and 81, with complementary plates arranged at 82', 83', 84', 85', 86' and 81' for receiving a secondary electron emission from each of the successive plates of the series. The secondary emission emitted from one plate is directed to a succeeding plate as indicated by the arrows and will not pass to any other plate; that is, each plate a1-V though it is a secondary electron emitting plate also acts as a shield for the projection of electrons along the projectory indicated Iby the arrows.

The circuits for the several multiplier plates are shown in Fig. 1 wherein the pairs of complementary plates are interconnected and biased at diiiering positive potentials obtained from potential `source 58 shunted by potentiometer 88 having taps distributed thereon, as shown. That is, sets of plates ESI-8|' are connected to tap 88a; sets of plates 82 and 82 are connected to tap 88h; sets of plates 83 and 83' are connected to tap 88e; sets of plates 84 and 84 are connected to tap 88d; sets of plates 85 and 85 are connected to tap 88e; sets of plates 86 and 86' are connected to tap 88f; while sets of plates 81 and 81 connect to the output for delivering the multiplied output current. The progressive positive potentials which are applied to the plates ill- 81 and SIL-81', respectively, are such that there is a continued tendency for the secondary emission from the successive plates to travel in the paths indicated to the nal output plates 81 and 81 for multiplying at each plate thefnal multiplied current from 81 and 31' delivered to the output circuit 4l. Each of the surfaces of the multiplier plates are coated with secondary electron emitting material except plates 81 and 81' to insure the maintenance of high secondary electron emitting properties.

While various secondary electron emitting materials may be employed, I desire to designate particularly the use of caesium-activated beryllium-beryllium oxide, and rubidium-activated silver-silver oxide.

The ilat ribbon-like electron beam emitted by G is controlled in position by deflecting plates 1 and 8 in accordance with the control currents applied at input circuit 40 and sweeps the secondary electron emitting triangular shaped plates 19. The secondary electrons released from the triangular` shaped plates 1s strike plates 8l and 8|' along paths designated by the arrows in Fig. 2 but are prevented from striking the successive multiplier plates by shields 1Gb and 19o, and by the shielding effect between rear surfaces of each of the plates except along the discharge paths indicated by the arrows in Fig. 2.

The operation of the secondary electron multiplier is as follows: The -current is increased at each successive plate in the ratio of the secondary emission to the electrons striking it. The final plates S51-$1 are not composed of secondary electron emitting material. Therefore, the current due to all the electrons striking the plates is passed on from these plates into the output resistance 59. By this means, the output is amplified approximately by the product of the number of secondary emitting plates and the ratio of the secondary emission plates to the electrons striking them and the ratio of the secondary emission to primary electrons.

While I have described my invention in certain preferred embodiments, I realize that modications may be made in the arrangement and method employed and I desire that it be understood that no limitations upon my invention are intended other than may be imposed by the scope of the appended claims.

What I claim and desire to secure by Letters Patent of the United States is as follows:

1. An electron tube system comprising an electron discharge device for propagating an electron beam, means for controlling the angular sweep oi the electron beam, a plate system disposed in the path of said electron beam, said plate system having a substantially V-shaped recess therein disposed on an axis transverse to the angular sweep of the electron beam a secondary electron emitting coating on said plate system, said coating varying from a minimum per .unit section of said beam at substantially the central portion of the sweep path of said beam to a maximum at either of the limits of movement of said beam, a multiplicity of secondary electron collecting plates arranged in echelon with respect to each other and each provided with a secondary electron emitting coating thereon for multiplying thev discharge 0f secondary electrons in a trajectory path shielded by the .arrangement of said multiplicity of secondary electron collecting plates, an output circuit including the last of said secondary electron collecting plates and said plate system, and means for maintaining said secondary electron collecting plates at successively diilerent positive potentials increasing according to the distance of said secondary electron collecting plates from said plate system.

2. An electron beam tube comprising a generator of electrons for propagating a beam of electrons, a plate system disposed in the path of said beam of electrons, said plate system having an angularly shaped opening therein, with the apex thereof extending on an axis substantially transverse to the path of movement of the beam of electrons means for deflecting said beam of electrons for scanning said plate system, said plate system including secondary electron emitting means varying from a minimum per unit section of said beam at substantially the central position of the deiection path of said beam to a maximum at opposite limits of travel of the deflection path of the beam, and a multiplicity of auxiliary electrodes disposed about said plate system out of the path of said beam of electrons but in positions for collecting secondary electrons from said plate system, certain of said auxiliary electrodes including means for rendering the eld about said plate system substantially uniform while others of said auxiliary electrodes operate to collect secondary electrons from said plate system, and an output circuit included between said last mentioned auxiliary electrodes and said plate system.

3. An electron beam tube comprising a generator of electrons for propagating a beam of electrons, a plate system disposed in the path of said beam of electrons, said plate system having an angularly shaped opening therein with the apex thereof extending on an axis substantially transverse to the path of movement of the beam of electrons means for deiiecting said beam of electrons for scanning said plate system, said plate system including secondary electron emitting means varying from a minimum per unit section of said beam at substantially the central position of the deflection path of said beam to a maximum at opposite limits of travel of the deflection path of the beam, a multiplicity of auxiliary electrodes disposed about said plate system out of the path of said beam of electrons but in positions for collecting secondary electrons from said plate system, said auxiliary electrodes being disposed alternately concave and convex with respect to said plate system, each of the successive auxiliary electrodes having secondary electron emitting coatings'thereon except the last auxiliary electrodes of the series, means for maintaining said auxiliary electrodes at successively diierent positive potentials increasing according to the distance of said auxiliary electrodes from said plate system and an output circuit included between said plate system and the last of the auxiliary electrodes of said series.

4. An electron beam tube comprising a generator of electrons for propagating a beam of electrons, a plate system disposed in the path of said beam of electrons, said plate system having an angularly shaped opening therein with the apex thereof extending on an axis substantially transverse to the path of movement of the beam of electrons means for deecting said beam of electrons for scanning said plate system, said plate system including secondary electron emitting means varying from a minimum per unit section of said beam at substantially the central position of the deection path of said beam to a maximum at opposite limits of travel of the deection path of the beam, and a multiplicity of auxiliary electrodes disposed about said plate system out of the path of said beam of electrons but in positions for collecting secondary electrons from said plate system, said auxiliary electrodes being disposed on axes transverse to the path of said beam of electrons and being arranged alternately concave and convex with respect to said plate system on substantially curvilinear axes extending from an electron receiving position adjacent the front of said plate system to a position in the rear of said plate system, means for shielding all of said auxiliary electrodes beyond the auxiliary electrodes immediately adjacent said plate system from the direct series.

WALTER SOLLER.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 1,757,345 Strobel May 6, 1930 1,920,863 Hopkins, Jr. Aug. 1, 1933 2,086,904 Evans July 13, 1937 2,103,507 Zworykin Dec. 28, 1937 2,190,069 Hollmann Feb. 13, 1940 2,205,071 Skellett June 18, 1940 2,250,528 Gray July 29, 1941 2,372,450 Rojchman et al Mar. 27, 1945 2,408,702 Sziklai Oct. 1, 1946 

